Something Very Exciting About A Nearby Star

Something Very Exciting About A Nearby Star

1:00pm Mar 03, 2017
The possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system.
This illustration shows the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Scientists using the Spitzer Space Telescope and ground-based telescopes have discovered that there are seven Earth-size planets in the system.

Recently, seven rocky, Earth-like planets were discovered orbiting a nearby star, adding to a catalog of 3,500 known extrasolar or exoplanets. Of the many ways to find planets orbiting stars, the most productive has been what's called the transit method: measuring the change in brightness of a star when a planet passes in front of it.

But not every dip in brightness indicates an exoplanet.

Nathan Kirse, an undergraduate majoring in astronomy at the University of North Carolina in Asheville and a Kaleideum Planetarium volunteer, specializes in exoplanets. His research involves Kepler Objects of Interest, or KOIs. These are stars that may or may not have planets.


   Nathan Kirse interviewing for SciWorks    Radio at SCFSounds Studio. Credit:          Shawn Fitzmaurice      

There are 5,000 KOIs out there that need to have follow-up observations to know whether these are planets or not. I’m studying these exoplanets to show that these KOIs should not be included in future research for more experienced astronomers.

The big difference is that planets don’t have any color change when the planet crosses the face of the star, but when a star crosses the face of another star there is some color change that I’m trying to detect.

So, if a star gets by Nathan, we can tell an awful lot from that dip in light output.

If it’s a bigger planet, it’s going to cause a bigger dip in brightness when it goes across the face of its star. And so, the transit method gives you an estimate of the size of these planets, assuming that you know the size of the star.

From there, we can use some basic math to learn the density and other important stuff about the planet.

Recently, astronomers confirmed something very exciting about the nearby star Trappist-1.

Astronomers are very excited about this discovery because it shows that Earth-sized planets, even Earth-sized planets that are in the habitable zone of their star, are not that uncommon. We found seven Earth-sized planets, around the same star, only 40 light years away. Forty light years is like our back deck when it comes to looking at the galaxy as a whole.

It’s not much larger than Jupiter, so if our sun was a basketball, this star would be a golf ball. Since it’s so small, it doesn’t produce that much light.

Trappist 1-E is one of those planets that orbits in the habitable zone of Trappist-1, and it receives about the same amount of light as Earth does. So that means that it could be about the same temperature as Earth.

Which means there could be liquid water, which we think life needs to get started. But here’s something else that's interesting about this planet…

Since Trappist-1 is such an incredibly dim star, it has to orbit really, really close to Trappist-1 to get the same amount of light as Earth.

According to Johannes Kepler’s famous second law, the closer a planet is to its star, the faster it moves.

So, Trappist 1E orbits in just six days.

...which is a very short year.

Also, since they’re so close to each other, that means that, if you were to be on the surface of one these planets, the other planets wouldn’t look like pinpoints of light, like they do on Earth. They are actually so close together that the other worlds would look as big as the moon in that sky, or even bigger.

Trappist-1 and its planets are only 40 light years away. Still, it would take about a million years to get there in a spaceship. So, why bother studying the system?

You know, it’s not that astronomers are wrapped in some kind of delusion that we’re going to be able to travel to these planets any time soon. The reason that we study exoplanets - worlds that we may never set foot on - there are many reasons, but I think the main reason is to answer the question, “Are we the only life in the universe?” And so the reason that Trappist-1 is so important is that these planets are close enough that we can actually make useful observations of them. We can answer that question in the near future with telescopes like the James Webb telescope to try and find oxygen in the atmospheres of these planets. That would be a huge sign that there is life on these planets. It would be huge.

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